Data traffic in mobile telecommunications networks is continually increasing. Consequently, operators are deploying heterogeneous access networks that make use of multiple radio access technologies (RATs) in order to provide greater capacity, particularly in high traffic areas and areas that otherwise have poor network coverage. Typically, the radio access technologies used by these heterogeneous access networks include Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE), and Wi-Fi/WLAN. In this regard, both the UMTS and LTE standards are defined by the 3rd Generation Partnership Project (3GPP), and the relevant 3GPP standards therefore define capabilities for handling load sharing between these 3GPP RATs (i.e. between a UMTS Radio Access Network (UTRAN) and an Evolved UTRAN (EUTRAN)). In contrast, the Wi-Fi/WLAN standards are defined by the Institute of Electrical and Electronics Engineers (IEEE), and neither the IEEE standards nor the 3GPP standards define capabilities for handling load sharing between Wi-Fi/WLAN and the 3GPP RATs.
In particular, for most currently available user terminals, when the user terminal is within the coverage of both a Wi-Fi RAN/WLAN and a 3GPP RAN, the user terminal will automatically attempt to connect to the Wi-Fi RAN/WLAN and will detach from the 3GPP RAN. Therefore, the decision to move from the 3GPP RAN to the Wi-Fi RAN is made without having considered the load and/or performance of either RAN, and can result in a reduction in performance that is detrimental to both the networks and the user. In particular, having the user terminal make an uninformed decision to move from the 3GPP RAN to the Wi-Fi RAN can result in an overload in the Wi-Fi RAN and/or underutilisation of the 3GPP RAN. Moreover, as the Wi-Fi RAN and 3GPP RAN are part of separate domains that use different management systems, different paradigms, different identities etc., there is no mechanism that allows either network to determine that the performance has deteriorated due to the move from the 3GPP RAN to the Wi-Fi RAN.